BIO 1004 Chapter 9: The Special Senses

What are sensations?

the conscious or subconscious awareness of a change in the internal or external environment

What is perception?

the awareness of a sensation

What partr of the brain is responsible for detecting and creating sensastions?

the cerebrum

What is projection?

when the cerebrum sends the sensation back to the region from where it originated so that it appears that the sensation is occurring in that area of the body

What is sensory adaptation?

repeated stimulation by a specific stimulus can reduce the effects of that stimulus on the body

What are the types of general senses?

temperature, pressure, touch, stretch, chemoreceptors, and pain

What monitors temperature?

thermoreceptors

What detects pressure, touch, and stretch?

mechanoreceptors

What do chemoreceptors do?

monitor chemical and fluid levels in the body

What detects pain?

nociceptors

What are the types of special senses?

smell, taste, vision, hearing, and equilibrium

What kind of sense is smell?

a chemical sense

What is a chemical sense?

chemicals react with smell receptors to produce a sensation

What are olfactory receptors?

neurons that respond to chemicals by producing smell impulses, these impulses are carried to the cerebrum

What are smell sensations created by?

the olfactory bulbs

What are supporting (sustentacular) cells?

columnar epithelial cells that make up the mucous membrane lining in the nasal cavity, can produce new olfactory receptor cells

When a human becomes used to a smell, what do humans develop towards that smell?

adaptations

What type of sense is taste?

chemical

Where are the receptors for taste located?

taste buds

How many taste buds do humans have?

about 10,000

Where are taste buds located?

on the tongue, larynx, pharynx, and soft palate

What are papilae?

elevations on the tongue that contain the taste buds, give the tongue a rough appearance

What are the types of cells associated with taste buds?

gustatory receptor cells and basal cells

What are gustatory receptor cells?

detect chemicals in food, may contain microvilli

What are microvilli?

small hairs often located in gustatory receptor cells

What are basal cells?

produce new support cells that can then develop into new gustatory receptor cells

What are the 4 primary taste sensations associated with human taste buds?

sour, salty, sweet, and bitter

Where is sour detected on the tongue?

along the sides

Where is salty detected on the tongue?

near the tip

Where is sweet detected on the tongue?

at the tip

Where is bitter detected on the tongue?

at the posterior

What are the external structures associated with sight?

eyelids (aka palpebrae), eyelashes, lacrimal glands, and extrinsic eye muscles

What is the purpose of eyelids?

shade the eyes during sleep and protect the eyes from sunlight, spread lubricating fluid over the surface of the eye

What is conjunctiva?

thin mucous membrane associated with the eyelids, contains numerous goblet cells which secrete mucous

What are the purpose of eyelashes?

protect the eyes from dust and foreign debris

What are glands of zeis?

specialized sebaceous glands located at the base of each eyelash

What is a sty?

an infection of the glands of zeis

What are lacrimal glands?

secrete lacrimal fluid (tears) through lacrimal ducts onto the surface of the eyeball, this fluid lubricates and protects the eyeball

What is lacrimal fluid composed of?

water, salts, mucus, and lysozyme

What is lysozyme?

an enzyme that kills bacteria

What are the extrinsic eye muscles?

adjust and position the eyeball

What are the external parts of the eyeball?

cornea, sclera, and pupil

What is the cornea?

a nonvascular covering that surrounds the iris, also involved in focusing light on the lens

What is the iris?

the colored portion of the eye

What is the sclera?

the white portion of the eye

What is the pupil?

a hole in the center of the iris, light passes into the eye through the pupil

How does the pupil change size?

muscles can adjust the size of the pupil based on the amount of light presence

What are the internal parts of the eyeball?

the choroid, the ciliary body, the retina, and the lens

What is the choroid?

lines the internal surface of the sclera, provides nutrients to the posterior surface of the retina

What does the ciliary body consist of?

the ciliary processes and ciliary muscle

What do the ciliary processes do?

secrete a fluid known as aqueous humorq

What is the ciliary muscle?

smooth muscle that alters the shape of the lens for near or far vision

What is the retina?

inner coat of the eyeball, lines the posterior portion of the eyeball and is highly vascular

What are the parts associated with the retina?

optic disc, rods, cones, macula lutea, fovea centralis, and the blind spot

What is the optic disc?

the site where the optic nerve exits the eyeball

What are rods?

photoreceptors that detect black and white light, allow us to see shape and movement

What are cones?

allow for color vision

What is the macula lutea?

the center of the posterior portion of the retina

What is the fovea centralis?

a small depression in the center of the macula lutea that only contains cones, this region provides resolution to our vision

What is the blind spot?

another name for the optic disc, lacks rods and cones

What is a detached retina?

often the result of trauma, can cause blindness

What is the lens?

located posterior to the pupil, primarily protein in composition, involved in focusing the object that one is observing

What holds the lens in place?

the suspensory ligaments

What are cataracts?

a loss of transparency of the lens, can be caused by aging, trauma, exposure to UV light, and certain medications, repaired by surgery

What are the chambers within the eyeball?

the anterior cavity and posterior cavity

What is the anterior cavity?

space anterior to the lens, filled with a watery fluid called aqueous humor

What is the posterior cavity?

space posterior to the lens, filled with a liquid called vistrous humor

What is intraocular pressure?

pressure within the eyeball, usually caused by the aqueous humor and vitreous humor

What is glaucoma?

excessively high intraocular pressure in the eyeball, can cause degeneration of the retina which may lead to blindness, can be repaired surgically

What is the physiology of sight?

1. light passes through the pupil and focuses on the optic disc by the lens

2. the optic nerve creates impulses that are carried to the optic chiasma of the brain

3. the optic chiasma creates the sensation of sight

What does the ear play a major role in?

providing auditory sensations and maintaining balance

What are the external parts of the ear?

the auricle (pinna) and the external auditory meatus (canal)

What is the auricle (pinna)?

composed of elastic cartilage, forms the outer ear itself

What is the auricle composed of?

the helix and lobule

What s the external auditory meatus (canal)?

the tube that extends from the auricle to the tympanum (eardrum), runs through the temporal bone

What are the ceruminous glands?

line the external auditory meatus (canal), the wax glands that secrete cerumen (earwax)

What is the purpose of cerumen (earwax)?

prevents dust and debris from collecting in the external auditory meatus

What are the internal parts of the ear?

the tympanic membrane (eardrum), the eustachian or auditory tube, the auditory ossicles, the semicircular canals, and the cochlea

What is the tympanic membrane (eardrum)?

a thin layer of tissue between the external auditory meatus and the iner ear, helps to move sound waves deep into the ear

What is a perforated eardrum?

a hole in the tympanic membrane, characterized by extreme pain, usually caused by trauma

What is the eustachian or auditory tube?

connects the middle ear with the nasopharynx, this tube opens during swallowing and yawning, helps to regulate pressure in the middle ear

What are the auditory ossicles?

3 bones within the middle ear, held in place by ligaments, involved in moving sound waves into the inner ear

What are the 3 auditory ossicles?

the malleus, incus, and stapes

What are the semicircular canals?

3 of these, contain otoliths

What are otoliths?

involved in providing us with our balance and equilibrium

What is the cochlea?

resembles a snail shell, contains the spiral organ

What is the spiral organ?

houses receptors that receive sound waves, the organ of hearing

What are some disorders/medical terms to know?

otitis media, conjunctivitis, otalgia, tinnitus, vertigo, macular degeneration, expothalmos, anosmia, retinoblastoma

What is otitis media?

infection of the inner ear, usually caused by bacteria

What is conjunctivitis?

inflammation of the conjunctiva, aka pinkeye

What is otalgia?

earache

What is tinnitus?

a ringing in the ears

What is vertigo?

sensation of spinning

What is macular degeneration?

progressive degeneration of the retina dn the macula lutea, the main cause of blindness in those over the age of 65, currently no cure

What is exophthalmos?

bulging eyeballs, common sign of hyperthyroidism

What is asnosmia?

the inability to smell

What is retinoblastoma?

cancer of immature retinal cells